Emulsions are commonly used to improve aesthetics but they may also be applied to deliver active ingredients. Recently, a group of pigments known as carotenoids has been added to emulsions as an active compound mainly due to their antioxidant properties. The stability of these formulations is a critical parameter for both, pharmaceutical and cosmetics industry. Therefore, in this study two analytical methods, multiple light scattering and laser diffraction, were tested to determine the stability of various emulsions containing carotenoids (β-carotene, lycopene, astaxanthin). Even small changes in stability of emulsions were determined very early. The results of both methods proved that the type of carotenoid used did not influence the emulsions' stability. The stability of emulsions depends mainly on the preparation methods and on the type of emulsifier applied.
Keywords: carotenoids; particle size; semisolid formulations; stability studies.